Tape measure with compact retraction system

ABSTRACT

A tool, such as a tape measure, including a spring-based retraction system is shown. Various spring-based retraction system embodiments are configured to decrease the size occupied by the spring within the tape measure housing, which consequently reduces tape measure housing size providing a more compact tape measure. Various spring-based retraction system embodiments are configured to control retraction of the tape measure in a manner that reduces whip or otherwise controls tape blade retraction. Some retraction system embodiments utilize a reduction gear train, and others utilize a compression spring and a transmission system that converts rotational movement of the tape reel to axial movement, which compresses the spring.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

The present application is a continuation of U.S. application Ser. No.15,782,978, filed on Oct. 13, 2017, which is a continuation ofInternational Application No. PCT/US2017/055166, filed on Oct. 4, 2017,which claims the benefit of and priority to U.S. Provisional ApplicationNo. 62/404,635, filed on Oct. 5, 2016, which are incorporated herein byreference in their entireties.

BACKGROUND OF THE INVENTION

The present invention relates generally to the field of tools. Thepresent invention relates specifically to a tape measure, measuringtape, retractable rule, etc., that includes a compact spring retractionsystem.

SUMMARY OF THE INVENTION

One embodiment of the invention relates to a tape measure including aspring based retraction system. The tape measure includes a tape reeland a measuring tape wound on the tape reel. A spring is coupled to thetape blade or tape reel so that the spring stores energy duringextension of the tape blade out of the tape measure housing and releasesenergy to drive tape blade uptake onto the tape reel during taperetraction.

In one embodiment, the tape measure includes a gear train rotatablycoupling the tape reel to the spring. In a specific embodiment, thespring is a spiral spring coupled to a post (e.g., a central post, axle,etc.) such that the spiral spring is wound around the post during tapeextension. In some such embodiments, the gear train is configured toprovide gear reduction between the tape reel and the spring such thatthe number of rotations the spring experiences during winding is lessthan the number of rotations experienced by the tape reel during tapeextension. In various embodiments, the gear reduction is greater than 2to 1, and more specifically is at least 3 to 1. In specific embodiments,the gear reduction allows for a lower spring length (and a lower maximumdiameter in the case of spiral springs) to achieve a given spring torquelevel as compared to conventional tape measures without gear reduction.

In various embodiments, the gear train is a planetary gear train, andthe planetary gear train includes a central (“sun”) gear rigidly coupledto the tape reel, a ring gear rigidly coupled to a spring spoolsurrounding the spiral spring, such that the ring gear rotates with thespring spool, a gear carrier rigidly fixed to the central post, and atleast two planet gears supported by the gear carrier such thatrotational motion is translated between the tape reel and the springspool. In specific embodiments, the gear carrier and planetary gears arelocated within and surrounded by at least one of the tape reel and thespring spool. In specific embodiments, the sun gear and ring gearsurround and are coaxial with at least one of the central post, thespring spool and/or the tape reel. In specific embodiments, theplanetary gears are spaced around and equidistance from the centralpost.

In another embodiment, the spring is a spiral spring positioned to windaround a spring axis, and the spiral spring is located outside of thetape reel at a position such that the spring axis is non-parallel to arotational axis of the tape reel. In a specific embodiment, the springaxis is perpendicular to the rotational axis of the tape reel. Invarious embodiments, the tape measure includes a gear train that changesdirection of rotational movement of the tape reel in order to driverotation of the spiral spring about the spring axis. In a specificembodiment, the gear train includes a first bevel gear engaging the tapereel, and a second bevel gear perpendicular to the first bevel gear. Insuch embodiments, the second bevel gear is driven by the first bevelgear during tape extension to rotate about the spring axis, and thesecond bevel gear is coupled to the spiral spring.

In another embodiment, the spring is a compression spring, and the tapemeasure includes a transmission system coupled between the tape reel andthe compression spring. The transmission system converts rotationalmotion of the tape reel to non-rotational (e.g., axial) compression ofthe compression spring. In one embodiment, the compression spring islocated within the tape reel and surrounds a central axis of the tapereel, and the transmission system includes a plate contacting an end ofthe compression spring. Rotation of the tape reel causes the plate totranslate in a direction along the central axis causing compression ofthe compression spring. In a specific embodiment, the plate includesgear teeth along its outer edge that engage cooperating gear teethformed along the inner surface of the tape reel, and the plate alsoincludes a threaded central opening that engages cooperating threadsalong a central post. In a specific embodiment, the central post isco-axial with the compression spring and the tape reel. In anotherembodiment, the plate includes a helical thread formed along an outerperipheral edge of the plate, and an inner surface of the tape spoolincludes a helically threaded surface that engages the helical thread ofthe plate.

Another embodiment relates to a tape measure. The tape measure includesa housing, a shaft coupled to the housing, a tape reel rotatably mountedwithin the housing around the shaft, and the tape reel includes aradially outward facing surface and a radially inward facing surfacedefining an interior reel cavity. The tape measure includes an elongatetape blade wound around the radially outward facing surface of the tapereel, and the elongate tape blade has an upper surface with a concaveprofile when extended from the housing. The tape measure includes aspiral spring located at least partially within the interior reel cavityand at least partially surrounded by the elongate tape blade in theradial direction. The spiral spring is coupled between the tape reel andthe shaft such that when the elongate tape blade is unwound from thetape reel to extend from the housing the spiral spring stores energy andthe spiral spring releases energy driving rewinding of the elongate tapeblade on to the tape reel. The tape measure includes a reduction geartrain rotatably coupling the spiral spring to the tape reel such that,during extension of the elongate tape blade from the housing, each fullrotation of the tape reel is translated into less than a full rotationof the spring. The tape measure includes a hook assembly coupled to anouter end of the elongate tape blade.

Another embodiment relates to a tape measure. The tape measure includesa housing and a tape reel rotatably mounted within the housing. The tapereel includes a radially outward facing surface and a radially inwardfacing surface defining an interior reel cavity. The tape measureincludes an elongate tape blade wound around the radially outward facingsurface of the tape reel. The elongate tape blade comprises a metal coreand a coating layer, and the metal core has an average cross-sectionalarea, TA. The tape measure includes a spring coupled to the tape reelsuch that when the elongate tape blade is unwound from the tape reel toextend from the housing the spring stores energy and the spring releasesenergy driving rewinding of the elongate tape blade on to the tape reel.The spring has an average cross-sectional area, SA, wherein TA/SA isless than 0.9.

Another embodiment relates to a tape measure. The tape measure includesa housing, a tape reel rotatably mounted within the housing, and thetape reel includes a radially outward facing surface and a radiallyinward facing surface defining an interior reel cavity. The tape measureincludes an elongate tape blade wound around the radially outward facingsurface of the tape reel, wherein the elongate tape blade has a maximumextended length, TL. The tape measure includes a spring coupled to thetape reel such that, when the elongate tape blade is unwound from thetape reel to extend from the housing, the spring stores energy and thespring releases energy driving rewinding of the elongate tape blade onto the tape reel. The tape measure includes a total spiral springlength, SL, and TL/SL is greater than 2.52.

Another embodiment relates to a tape measure. The tape measure includesa housing, and a tape reel rotatably mounted within the housing. Thetape reel includes a radially outward facing surface and a radiallyinward facing surface defining an interior reel cavity. The tape reelincludes a reel area, RA, located within the radially outward facingsurface of the tape reel. The tape measure includes an elongate tapeblade wound around the radially outward facing surface of the tape reel,and the elongate tape blade has a maximum extended length, TL. TL/RA isgreater than 6.6.

Another embodiment relates to a tape measure including a housing, ashaft, and a tape reel rotatably mounted within the housing around theshaft. The tape reel includes a radially outward facing surface and aradially inward facing surface defining an interior reel cavity. Thetape measure includes an elongate tape blade wound around the radiallyoutward facing surface of the tape reel. The tape measure includesspiral spring coupled between the tape reel and the shaft such that,when the elongate tape blade is unwound from the tape reel to extendfrom the housing, the spring stores energy and the spiral springreleases energy driving rewinding of the elongate tape blade on to thetape reel. The tape measure includes a turn differential mechanismrotatably coupling the spiral spring to the tape reel such that, duringextension of the elongate tape blade from the housing, each fullrotation of the tape reel is translated into less than a full rotationof the spring. The tape measure is in a retracted state when a maximumamount of the elongate tape blade is wound around the radially outwardfacing surface of the tape reel, and the tape measure is in an extendedstate when a minimum amount of the elongate tape blade is wound aroundthe radially outward facing surface of the tape reel. The tape reelrotates in a first direction a number of times from the retracted stateto the extended state, Tape Reel Turns, wherein a first end of thespiral spring rotates about the shaft a number of times, Spring Turns,and wherein Tape Reel Turns/Spring Turns is greater than 0.94.

Another embodiment relates to a tape measure including a housing, ashaft, a tape reel rotatably mounted within the housing around theshaft. The tape reel includes a radially outward facing surface and aradially inward facing surface defining an interior reel cavity. Thetape reel includes an elongate tape blade wound around the radiallyoutward facing surface of the tape reel, and the elongate tape bladecomprises a moment of inertia, MIT. The tape measure includes a spiralspring coupled between the tape reel and the shaft such that, when theelongate tape blade is unwound from the tape reel to extend from thehousing, the spring stores energy and the spiral spring releases energydriving rewinding of the elongate tape blade on to the tape reel, andthe spiral spring comprises a moment of inertia, MIS. The tape measureincludes a turn differential mechanism rotatably coupling the spiralspring to the tape reel such that, during extension of the elongate tapeblade from the housing, each full rotation of the tape reel istranslated into less than a full rotation of the spring. MIT/MIS is lessthan 0.8.

Another embodiment relates to a tape measure including a housing, a tapereel rotatably mounted within the housing. The tape reel includes aradially outward facing surface and a radially inward facing surfacedefining an interior reel cavity. The tape measure includes an elongatetape blade wound around the radially outward facing surface of the tapereel. The tape measure includes a spiral spring coupled between the tapereel and the shaft such that, when the elongate tape blade is unwoundfrom the tape reel to extend from the housing, the spring stores energyand the spiral spring releases energy driving rewinding of the elongatetape blade on to the tape reel. The tape measure includes the elongatetape blade comprises a metal core and a coating layer, and the metalcore has an average thickness, TT, and the spiral spring has an averagethickness, ST. TT/ST is less than 0.73.

Another embodiment relates to a tape measure includes a housing, and atape reel rotatably mounted within the housing. The tape reel includinga radially outward facing surface and a radially inward facing surfacedefining an interior reel cavity. The tape measure includes an elongatetape blade wound around the radially outward facing surface of the tapereel. The tape measure includes the tape reel comprises a diameter, D,measured across the radially outward facing surface of the tape reel,wherein the elongate tape blade has a total maximum extended length ofTL, wherein TL/D is greater than 237.

Additional features and advantages will be set forth in the detaileddescription which follows, and, in part, will be readily apparent tothose skilled in the art from the description or recognized bypracticing the embodiments as described in the written description andclaims hereof, as well as the appended drawings. It is to be understoodthat both the foregoing general description and the following detaileddescription are illustrative.

The accompanying drawings are included to provide a furtherunderstanding and are incorporated in and constitute a part of thisspecification. The drawings illustrate one or more embodiments andtogether with the description serve to explain principles and operationof the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a first exploded view of a tape measure, according to anillustrative embodiment.

FIG. 2 is a second exploded view of the tape measure of FIG. 1,according to an illustrative embodiment.

FIG. 3 is a partial cut-away view of the tape measure of FIG. 1 showinga gear train, according to an illustrative embodiment.

FIG. 4 is a perspective view of a tape measure reel and retractionsystem including a gear train, according to another illustrativeembodiment.

FIG. 5 is a perspective view of the tape measure reel and retractionsystem of FIG. 4 with the spiral spring removed, according to anillustrative embodiment.

FIG. 6 is an exploded view of a tape measure, according to anotherillustrative embodiment.

FIG. 7 is a perspective view of the tape measure reel and retractionsystem of the tape measure of FIG. 6, according to an illustrativeembodiment.

FIG. 8 is a perspective view of a tape measure reel and retractionsystem including a compression spring, a threaded compression plate andan internally threaded tape reel, according to another illustrativeembodiment.

FIG. 9 is a perspective view of the threaded compression plate of FIG.8, according to an illustrative embodiment.

FIG. 10 is a cross-sectional view of the tape measure of FIG. 1,according to an illustrative embodiment.

FIG. 11 is a cross-sectional view of the tape blade of the tape measureof FIG. 1, according to an illustrative embodiment.

FIG. 12 is a perspective view of the tape blade, tape reel and spiralspring of the tape measure of FIG. 1, according an illustrativeembodiment.

DETAILED DESCRIPTION

Referring generally to the figures, various embodiments of a tapemeasure are shown. Various embodiments of the tape measure discussedherein include an innovative retraction system designed to provide for avariety of desired retraction characteristics, including controlledretraction speed, reducing the amount of whip experienced during bladeretraction (e.g., the tendency of the tape measure blade to bend or snapback on itself during fast retraction), and/or providing a retractionsystem that allows for a more compact tape measure without sacrificingtape length or retraction performance.

As will generally be understood, in certain tape measure designs, aspring stores energy during tape blade extension, and applies force to areel causing the tape blade to wind on to a reel during tape bladeretraction. Various aspects of spring design, such as spring energy,torque profile, spring constant, etc., are selected to ensure thatoperation of the spring causes satisfactory level of tape retraction. Insuch tape measures, the spring design is a function of a variety ofparameters that relate to retraction of the tape measure blade,including tape measure blade width, length, shape and material, frictionwithin the tape measure spool/retraction system, mechanical efficiencyof translation of spring energy to tape blade retraction, the desiredspeed/acceleration of the tape measure blade during retraction, etc.Thus, for a given set of tape measure mechanical parameters and a givendesired retraction speed/acceleration, the spring system within the tapemeasure needs to store and release a given amount of energy during taperetraction.

In typical tape measure designs, a spiral spring is used to provide theretraction energy, and in such designs, spiral spring length, widthand/or thickness are the typical spring parameters adjusted to providemore or less retraction energy as needed for particular designs. Forexample, in such conventional tape measures, a thicker spiral spring istypically used to generate retraction force needed for a longer tapemeasure blade, a heavier tape measure blade, a faster retraction speed,wider tape blades, blades with deeper curvature, etc. As discussedherein, Applicant has developed various innovative tape measure bladeretraction systems that provide a desired level of spring energy whileutilizing a relatively short or small volume spring, while maintaining arelatively small tape measure housing (e.g., a tape measure outerdiameter), and/or while providing desired retraction characteristics. Insome instances, having a smaller outside diameter of the spooled bladeon the reel is favorable over a larger outside blade diameter becausethe housing of the tape measure can be reduced accordingly. A smallerhousing is generally favorable to fit comfortably within a user's hand.

In such embodiments, the spring is configured to deliver high levels oftorque despite its small size, allowing for a relatively small sizedspring to cause retraction of a relatively long tape blade. Thus,Applicant's tape measure designs discussed herein are believed to allowfor highly compact tape measures (for a given tape length) not achievedin prior designs. In such embodiments, the high torque and compactspring is generally thicker, shorter, wider, has a highercross-sectional area and/or occupies a smaller space within the tapemeasure for a given tape length than believed achievable with priordesigns.

Some prior tape designs use multiple spiral springs coupled in series toachieve a compact design. However, in such designs, while diameter ofthe spring area of the tape measure is decreased, total amount of springlength is still relatively high and simply shifted in the widthdirection and the width of the spring cavity is increased. Accordingly,in some embodiments, the tape measure discussed herein achieves a highlycompact tape measure utilizing a single spiral spring, and in at leastsome embodiments, Applicant believes that such designs improve variousmeasurements of compactness (e.g., ratio of tape length to springlength, ratio of tape metal thickness to spring thickness, ratio of tapemetal cross-sectional area to spring cross-sectional area, ratio of tapesteel moment of inertia to spring moment of inertia, tape length to tapereel diameter, tape length to tape reel area, ratio of tape reel turnsto spring turns, etc.) even compared to such multi-spring tape measuredesigns. In alternative embodiments, multiple spiral springs (e.g., inseries and/or in parallel) can be used.

In a specific embodiment, the tape measure discussed herein utilizes ahigh torque, compact spiral spring and includes a turn reductionmechanism (e.g., a reduction gear train) located between a tape reel andthe spiral spring that results in a highly compact tape measure notachieved in prior tape measure designs. In such embodiments, thereduction gear train decreases the number of rotations the spiral springexperiences for every rotation of the tape reel upon tape extension. Insuch embodiments, the spiral spring of the tape measure embodimentsdiscussed herein utilizes spring width, thickness, material, etc. ratherthan spring length to generate a given torque level/energy level neededto provide a particular level of retraction speed, acceleration, etc.,as desired for a particular length/size of measuring tape. By decreasingspring length, the size/diameter of the space occupied by the springwithin the tape measure can be reduced (i.e., an increase in energydensity), which in turn provides a highly compact tape measure, for agiven tape length.

Further, in contrast to some prior tape designs that utilize gearing(e.g., long-length, greater than 50 ft. long, flat tapes, crank-basedmanual retraction tapes, etc.), the compact designs discussed herein areprovided in tape measures having highly robust, high standout,concave/convex metal tape blades, in at least some embodiments.Similarly, in comparison to some such prior geared tape measures, themetal tape blades discussed herein are relatively wide, allowing forgood number/indicia readability and standout, and further may beequipped with a robust hook assembly fixed to the end of the metal tapeblade. As such, Applicant believes that prior tape measure designs wereunable to achieve the high levels of compactness in a self-retractingtape measure utilizing this type of metal blade.

In another embodiment, the tape measure includes a compression spring(e.g., a helical compression spring, a wave spring, etc.) and atransmission system for converting rotational movement of the tape reelto spring compression. In such embodiments, the compression spring maybe positioned within the tape measure housing in a way that allows adesired level of energy to be stored within the spring while alsoreducing total tape measure size (e.g., as compared to a standard spiralspring design). In such embodiments, a component of the tape measure,such as a central post or inner surface of the tape reel, includesthreading which translates rotational movement of the tape reel totranslational or axial movement of a plate which compresses thecompression spring during tape retraction.

Referring to FIGS. 1, 2, 10 and 11, a tape measure, measuring tape,retractable rule, etc., such as tape measure 10, is shown according toan illustrative embodiment. In general, tape measure 10 includes ahousing 12 having a first part 14 and a second part 16. Tape measure 10includes a tape blade 18, and in the retracted position shown in FIGS. 1and 2, tape blade 18 is wound or coiled onto a tape reel 20. In general,tape blade 18 is an elongate strip of material including a plurality ofgraduated measurement markings, and in specific embodiments, tape blade18 is an elongate strip of metal material (e.g., steel material) thatincludes an outer most end coupled to a hook assembly 21. Tape blade 18also has a concave/convex profile as shown in FIG. 11 that improvesstandout/rigidity. As will generally be understood, tape blade 18 hasthe concave/convex profile when extended from housing 12, but agenerally flat profile/shape when wound around reel 20.

In various embodiments, housing 12 can be a clam shell housing. As shownin FIG. 1, housing 12 includes an opening that allows tape blade 18 toenter and exit housing. In various embodiments, tape measure 10 includesa locking mechanism, such as a slide lock or auto lock, that locks tapeblade 18 at a desired extended position as desired by the user.

In general, tape reel 20 is rotatably mounted to shaft, shown as an axleor post 22, that is supported from housing 12. In one embodiment, post22 is rigidly connected (e.g., rotationally fixed) relative to housing12, and in another embodiment, post 22 is rotatably connected to housing12 such that post 22 is allowed to rotate relative to housing 12 duringtape extension or retraction.

Tape measure 10 includes a spring, shown as spiral spring 24. Ingeneral, spiral spring 24 is coupled between post 22 and tape 18 (ortape reel 20) such that spiral spring 24 is coiled or wound to storeenergy during extension of tape 18 and is unwound, releasing energydriving rewinding of tape 18 onto tape reel 20 during retraction of tape18. In specific embodiments, spiral spring 24 is mounted within a springspool 26, and as explained in more detail below, spring spool 26includes a toothed section that acts as a portion of a reduction geartrain. In embodiments utilizing spring spool 26, an inner end of spring24 is coupled to post 22, and an outer end of spring 24 is directlycoupled to spring spool 26. In such embodiments, spring 24 is coupled totape reel 20 via the connection to spring spool 26 and the gear train asdiscussed below. In a specific embodiment, tape measure 10 includes onlya spiral spring located within a spring spool. In another embodiment,tape measure 10 includes two or more spiral springs for driving taperetraction.

As shown best in FIG. 1, in one embodiment, tape measure 10 includes areduction gear train, shown as epicyclic or planetary gear train 30,that is coupled between tape reel 20 and spiral spring 24. In suchembodiments and as will be discussed in more detail below, gear train 30allows for tape measure 10 to be more compact (as measured by thevarious compactness measurements discussed herein) than believed to beachieved with prior tape measure designs. In general, the reduction geartrain of tape measure 10 provides gear reduction between tape reel 20and spiral spring 24 such that for each rotation of tape reel 20 (e.g.,during tape extension), spiral spring 24 experiences less than onerotation of winding. In specific embodiments, the gear reductionprovided by gear train 30 is at least 1.5 to 1, specifically is at least2 to 1, more specifically is at least 3 to 1, and more specifically isbetween 1.8 to 1 and 9 to 1.

In a specific embodiment, tape measure 10 is in a retracted state when amaximum amount of the tape blade 18 is wound around the radially outwardfacing surface of the tape reel 20. Tape measure 10 is in an extendedstate when a minimum amount of tape blade 18 is wound around theradially outward facing surface of the tape reel 20. The tape reelrotates in a first direction a number of times from the retracted stateto the extended state, Tape Reel Turns. A first end of the spiral springrotates about the post 22 a number of times between a fully relaxedstate in which the spring 24 imparts no torque between the post 22 andthe spring spool 26 (i.e., the spring 24 is not preloaded) and the fullyretracted state, Spring Turns. In various embodiments the ratio of theseturns, Tape Reel Turns/Spring Turns is greater than 0.94. In variousembodiments, Tape Reel Turns/Spring Turns is greater than 1.0. Invarious embodiments, Tape Reel Turns/Spring Turns is greater than 1.7.In various embodiments, Tape Reel Turns/Spring Turns is greater than1.8. In various embodiments, Tape Reel Turns/Spring Turns is greaterthan 1.9. In various embodiments, Tape Reel Turns/Spring Turns isgreater than 2.0. In various embodiments, Tape Reel Turns/Spring Turnsis greater than 2.5. In various embodiments, Tape Reel Turns/SpringTurns is greater than 3.0.

In specific embodiments, the gear reduction of gear train 30 and thetape reel turn to spring turn ratio is determined by determining thenumber of rotations that the tape reel 20 and experienced during fullextension of tape blade 18 (i.e., extension from the fully retractedposition to the fully extended position), determining the number oftimes an end of the spring 24 circles around the post 22 from a fullyrelaxed position (i.e., in which the spring 24 is not pretensioned) to afully retracted position (i.e., in which the tape blade 18 is fullyextended or the spring 24 is fully wound against the walls of theinterior reel cavity 124), and utilizing these rotations to calculatethe tape reel turn to spring turn ratio. In an illustrative embodiment,Spring Turns is the number of times that the tape reel 20 can rotatebetween a state in which the spring 24 is wound solid around the post 22and a state in which the spring 24 has fully unwound into the walls ofthe interior reel cavity 124 (e.g., assuming that the length of the tapeblade 18 does not allow prevent the spring 24 to fully unwind). Ingeneral, measurement of spring turns is measured by counting the numberof times that the outer end of spring 24 (that is coupled to springspool 26) rotates around post 22 to coil the spring 24 around the post22 in the fully retracted position. As will generally be understood,given a particular torque profile of spiral spring 24 the number ofturns experienced by spiral spring 24 may vary at different pointsduring tape extension (e.g., the relation is non-linear for some springdesigns), and thus, by calculating the tape reel turn to spring turnratio based on the turns experienced to achieve full extension, aconsistent measure of the operation of gear train 30 is provided.

As will generally be understood, given a particular torque profile ofspiral spring 24 the number of turns experienced by spiral spring 24 mayvary at different points during tape extension (e.g., the relation isnon-linear for some spring designs), and thus, by calculating the tapereel turn to spring turn ratio based on the turns experienced to achievefull extension, a consistent measure of the operation of gear train 30is provided.

Applicant has found that by providing gear reduction between tape reel20 and spiral spring 24, the torque/energy of spiral spring 24 canprovide a desired level of torque while decreasing the total length ofspiral spring 24. In specific embodiments, by reducing the total lengthof spiral spring 24, the diameter of spiral spring 24 and of springspool 26 can be reduced, relative to spiral springs 24 with similartorque/energy in tape measures that do not utilize gear reduction asdiscussed herein. This reduction allows for a more compact tape measurefor a given tape length than believed achievable with prior tape measureand spiral spring designs.

In addition to spring length reduction, Applicant has developed springand gear train arrangements positioned within housing 12 and/or relativeto various components of tape measure 10 (e.g., relative to post 22,spring 24, tape reel 20, spring spool 26, etc.) that further provide acompact tape measure design. In one such compact design, as shown inFIG. 3, gear train 30 is positioned such that one or more component ofgear train 30 surrounds, rotates around or is co-axial with the axis ofrotation of tape reel 20 and/or with the winding axis of spring 24.Specifically, gear train 30 is positioned such that one or morecomponent of gear train 30 surrounds, rotates around or is co-axial withpost 22. In addition, the components of gear train 30 are located withinand surrounded by tape reel 20 and/or spring spool 26.

Further, as shown best in FIG. 10, spiral spring 24 and gear train 30are positioned in the widthwise direction of tape measure 10 to providefor a compact tape measure. For example, as shown in FIG. 10, at leastone gear of gear train 30 is positioned underneath/within tape reel 20and/or tape blade 18 such that at least one gear of gear train 30 is atleast partially surrounded by tape reel 20 and/or tape blade 18 in theradial direction of tape reel 20 (i.e., the vertical direction in theorientation of FIG. 10). In a specific embodiment, all of the gears ofgear train 30 are positioned underneath/within tape reel 20 and/or tapeblade 18 such that all of the gears of gear train 30 are at leastpartially surrounded by tape reel 20 and/or tape blade 18 in the radialdirection of tape reel 20.

Similarly, as shown in FIG. 10, tape reel 20 defines a radially outwardfacing surface 120 and a radially inward facing surface 122. Outwardfacing surface 120 is the surface of reel 20 around which tape blade 18is wound, and inward facing surface 122 defines an interior reel cavity124 within which spiral spring 24 (and spring spool 26) are received. Asshown in FIG. 10, spiral spring 24 is positioned at least partiallywithin interior reel cavity 124 and is also at least partiallysurrounded by tape reel 20 and/or tape blade 18 in the radial directionof tape reel 20 (i.e., the vertical direction in the orientation of FIG.10). In a specific embodiment, all of spiral spring 24 is positionedwithin interior reel cavity 124 and is surrounded by tape reel 20 and/ortape blade 18 in the radial direction of tape reel 20. In suchembodiments, no portion of spiral spring 24 extends in the widthdirection past the lateral most edges of tape blade 18 and/or of tapereel 20. Applicant believes that, in contrast to at least some priortape measure designs, by fitting both gear train 30 and spiral spring 24within tape reel 20 and/or within tape blade 18, a tape measure with acompact width dimension is provided while still providing the desiredlevel of spring torque for tape blade retraction.

Still referring to FIG. 10, in the specific embodiment shown, springspool 26 includes a radially inward facing surface 126 that defines aninterior spring spool cavity 128. In this arrangement, spring spool 26is at least partially received within spring spool cavity 128, andspiral spring 24 is at least partially located within spring spoolcavity 128. In a specific embodiment, spiral spring 24 is locatedentirely within spring spool cavity 128 such that no portion of spiralspring 24 extends laterally (e.g., in the width direction) past thelateral edges of spring spool 26.

Referring primarily to FIGS. 1 and 3, details of gear train 30 are shownand described, and as shown in FIG. 3, the left end wall 48 (in theorientation of FIG. 1) of tape reel 20 is removed to show the componentsof gear train 30 fully assembled. Gear train 30 includes a central orsun gear 40, an outer ring gear 42, a gear carrier 44 and at least twoplanetary gears 46.

As shown best in FIGS. 2 and 3, sun gear 40 is rigidly coupled to tapereel 20, and outer ring gear 42 is rigidly coupled to spring spool 26.In the specific embodiment shown, sun gear 40 is a gear structure thatextends inward from an inner surface of left end wall 48 of tape reel20, and outer ring gear 42 is formed from gear teeth extending radiallyinward from an inner, generally cylindrical surface of spring spool 26.In some such embodiments, sun gear 40 and tape reel 20 are integrallyformed from a single, contiguous and continuous piece of material, andring gear 42 and spring spool 26 are integrally formed from a single,contiguous and continuous piece of material. In such embodiments,Applicant has found that by integrally forming these components of geartrain 30 with certain components of tape measure 10 the complexityand/or size of gear train 30 can be reduced.

Planetary gears 46 are rotatably mounted to posts 50 of gear carrier 44and are located in between sun gear 40 and ring gear 42 in the radialdirection. As will be understood, planetary gears 46 translaterotational movement between tape reel 20 and spring spool 26, and atleast one of sun gear 40 and ring gear 42 rotates in a path aroundcenter post 22. In such embodiments, at least one of the sun gear 40 andring gear 42 is rigidly coupled to tape reel 20. As used herein, rigidlycoupled refers to components coupled together such that relativerotation between the components does not occur.

Specifically, referring to the orientation in FIG. 3, during extensionof tape 18 in the direction of arrow 52, tape reel 20 spins in thecounterclockwise direction around post 22, and similarly sun gear 40(which is rigidly connected to tape reel 20) spins in thecounterclockwise direction around post 22. Gear carrier 44 is mounted topost 22 via the rotationally fixed engagement between the square opening54 at the center of gear carrier 44, and the square outer perimetershape of post 22 prevents rotation of gear carrier 44 on post 22, whichin turn allows gear train 30 to operate as discussed herein. Thus,counterclockwise rotation of sun gear 40 drives rotation of planetarygears 46 in the clockwise direction around each post 50. Rotation ofplanetary gears 46 drives rotation of ring gear 42 in the clockwisedirection around post 22, and due to the rigid coupling between ringgear 42 and spring spool 26, spring spool 26 is also rotated in theclockwise direction around post 22.

Due to the coupling between a first/inner end of spiral spring 24 topost 22 and between a second/outer end of spiral spring 24 and springspool 26, rotation of spring spool 26 driven by gear train 30 causeswinding of spring 24 around post 22, thereby storing energy withinspiral spring 24. In a specific embodiment, the second/outer end ofspiral spring 24 is mechanically fastened to the inner surface of theouter wall of spring spool 26. As will be generally understood, whentape 18 is released following extension (e.g., following release of abrake mechanism), spiral spring 24 unwinds, driving the rotation of thecomponents of gear train 30 in directions opposite of those discussedabove regarding tape extension, which in turn drives tape reel 20 torotate in the clockwise direction winding tape blade 18 onto tape reel20.

It should be understood that in other embodiments, gear train 30 can bearranged in a variety of different ways to provide the size reductionand gear reduction discussed herein. In such embodiments, spring spool26 and therefore ring gear 42 is rigidly fixed relative to tape housing12, and center post 22 is rotationally coupled to housing 12. In suchembodiments, the gear carrier supporting planetary gears 46 moves in apath between ring gear 42 and sun gear 40 as center post 22 rotates,thereby winding spring 24 from its inner end coupled to center post 22.

As noted above, Applicant has determined a number of metrics related toor measuring the compactness of a tape measure. As discussed herein,utilizing these metrics of tape measure compactness, Applicant is ableto demonstrate that the designs discussed herein allow for more compacttape measures, for a given tape blade length, than believed achievablewith prior tape measure designs. Applicant believes that these highlevels of compactness are achieved without sacrificing retractionperformance. In addition, it should be understood that while the tapemeasure compactness metrics will be discussed in reference to tapemeasure 10 utilizing planetary gear train 30, the highly compact tapemeasures discussed herein are not limited to tape measures that utilizeplanetary gear train 30 and may be achieved utilizing various other tapemeasure designs that may be developed in light of the teachingscontained herein. For example, the turn reduction mechanism of tapemeasure 10 may also include one or more pulleys, a motor (such as anelectric motor), or other turn reducing component, and these componentsmay be utilized either alone or in combination with a reduction geartrain.

In various embodiments discussed herein, a compact, high torque spring,such as spiral spring 24, is used to provide retraction to tape measure10. In such designs, the spring of the tape measures discussed hereinprovide the additional torque through a spring that is more rigid butshorter in length than the spring of conventional tape measures.Applicant has found that such a design provides sufficient retractionforce while allowing the spring to occupy a smaller volume within thetape measure, which in turn allows for a more compact tape measure for atape of a given length.

Applicant has determined that one way the degree of compactness can bemeasured is by evaluating the length of tape blade 18, TL, relative tothe total length of the retraction spring(s) (e.g., spring 24), SL, fora given tape measure. As used herein, TL is the maximum length of tapeblade 18 that can be extended from tape housing 12. SL is the totallinear length of the spring(s) utilized to drive retraction of tape reel20. Regarding SL, in the context of a spiral spring, such as spring 24,SL is the total linear length of the metal material of the springmeasured between the inner end at coupled to center post 22 and theouter end coupled to spring spool 26, and is equal to the length of thestraight strip of metal from which the spiral spring is formed. In someinstances, SL may be referred to as the “active length” of the spring.In the context of tape measure design with more than one spring (e.g.,multiple spiral springs), SL is the linear length of one of the spiralsprings that drive retraction of tape reel 20.

In specific embodiments, the ratio of TL/SL is greater than 2.52,specifically is between 3 and 15, and more specifically is between 3.3and 6. In some embodiments, TL/SL is greater than 3, greater than 3.7,greater than 4, greater than 5. In specific embodiments, TL is between 6feet and 50 feet, and SL is between 5.3 feet and 22.7 feet. In specificembodiments, TL is between 15 ft. and 40 ft., and in even more specificembodiments, TL is 35 ft., is 30 ft., is 25 ft., or is 16 ft. In aspecific embodiment, tape measure 10 is a 25 foot tape measure in whichTL is 25 ft. having a TL/SL ratio of 3.36-3.73. In a specificembodiment, tape measure 10 is a 35 foot tape measure in which TL is 35ft. having a TL/SL ratio of 4-4.5, and specifically of 4.3. In aspecific embodiment, tape measure 10 is a 40 foot tape measure in whichTL is 40 ft. having a TL/SL ratio of 4.67-5.84. In a specificembodiment, tape measure 10 is a 50 foot tape measure in which TL is 50ft. having a TL/SL ratio of 13-16, specifically of 14 to 15, and morespecifically of 14.74.

The TL/SL ratios in prior art commercial tape measure designs thatApplicant is aware of are between 1.26-2.52 including single-springdesigns and multi-spring designs in which SL is the sum of the length ofthe multiple springs. The TL/SL ratios in prior art commercialmulti-spring-in-series tape measure designs that Applicant is aware ofare between 3.02-3.64 where SL is the length of one of the springs.

In some embodiments, tape measure 10 includes a plurality of springs,and SL is the length of one of the plurality of springs. In anotherembodiment, the tape measure 10 includes a plurality of springs, and SLis the summed total spring length, SL, and the tape blade 18 has amaximum extended length, TL, wherein TL/SL is greater than 1.75.

In various embodiments, the level of torque provided by spring 24 isprovided by a thicker metal material forming spring 24, rather thanincreased length, and in such embodiments, the degree of compactness oftape measure 10 can be measured by evaluating the thickness of the metalmaterial of spring 24 relative to the thickness of the metal material oftape blade 18. As shown in FIG. 11, in some embodiments, tape blade 18has a metal core 130 and a coating layer, such as a polymer coatinglayer 132. Metal core 130 of tape blade 18 has an average thickness, TT.As shown in FIG. 10, spring 24 has an average thickness, ST. In variousembodiments, because spring 24 is thicker (and therefore more rigid)than typical tape measure springs, the ratio of TT/ST of tape measure 10is lower than typical tape measures. In various embodiments, TT/ST isless than 0.72, specifically is between 0.1 and 0.7 and morespecifically is 0.43 to 0.61. In various embodiments, TT/ST is less than0.73, is less than 0.70, is less than 0.70, is less than 0.60, is lessthan 0.50, is less than 0.40, is less than 0.30, is less than 0.20, oris less than 0.10.

In a specific embodiment, tape measure 10 is a 25 foot tape measure inwhich TL is 25 ft. having a TT/ST ratio of 0.55-0.64. In a specificembodiment, tape measure 10 is a 35 foot tape measure in which TL is 35ft. having a TT/ST ratio of 0.4-0.45, and specifically of 0.43. In aspecific embodiment, tape measure 10 is a 40 foot tape measure in whichTL is 40 ft. having a TT/ST ratio of 0.4-0.45, and specifically of 0.43.In a specific embodiment, tape measure 10 is a 50 foot tape measure inwhich TL is 50 ft. having a TT/ST ratio of 0.3-0.35, and specifically of0.33.

The TT/ST ratios in prior art single-spring commercial tape measuredesigns that Applicant is aware of are between 0.88-1.15. The TT/STratios in prior art multi-spring commercial tape measure designs thatApplicant is aware of are between 0.73-0.76.

In various embodiments, tape blade 18 has an average tape width, TW. Invarious embodiments TW is greater than 10 mm, specifically is greaterthan 13 mm and specifically is 13-32 mm. Applicant believes that tapemeasure 10, utilizing the designs discussed herein, are compact despitehaving a relatively high width tape blade and easy to read tape blade18, and spring 24 is capable of tape retraction, even of the relativelywide tape blade, despite its small size. Thus, the tape measureembodiments discussed herein provide a high level of compactness (asmeasured by one or more of the compactness metrics discussed herein)while providing a spring with sufficient torque to retract a relativelywide (e.g., 13-32 mm) tape blade. This is in contrast to some compacttape measures that provide a compact housing by using a very narrow tapeblade.

As will generally be understood, the stiffness and therefore torqueapplied by spring 24 is not only a function of spring thickness, ST, butalso of spring width. Accordingly, the compactness of tape measure 10can be evaluated by comparing the average cross-sectional area, TA, ofmetal core 130 of tape blade 18 to the average cross-sectional area, SA,of spring 24 (e.g., average spring width times average springthickness). In various embodiments because spring 24 is thicker and/orwider than conventional tape measure springs, the ratio of TA/SA is lessthan that of conventional tape measure springs. In various embodiments,TA/SA is less than 0.9, specifically is less than 0.75, and morespecifically is between 0.4 and 0.65.

In the case of a tape measure with multiple springs coupled in parallel,SA is the sum of the cross-sectional area of all of the springs, but inthe case of a tape measure with multiple springs coupled in series, SAis the cross-sectional area of one of the springs. In variousembodiments, TA/SA is less than 0.98, less than 0.7, less than 0.6 andless than 0.5. In a specific embodiment, tape measure 10 is a 25 foottape measure in which TL is 25 ft. having a TA/SA ratio of 0.42-0.63. Ina specific embodiment, tape measure 10 is a 35 foot tape measure inwhich TL is 35 ft. having a TA/SA ratio of 0.4-0.5, and specifically of0.47. In a specific embodiment, tape measure 10 is a 40 foot tapemeasure in which TL is 40 ft. having a TA/SA ratio of 0.4-0.5, andspecifically of 0.46. In a specific embodiment, tape measure 10 is a 50foot tape measure in which TL is 50 ft. having a TA/SA ratio of 0.2-0.3,and specifically of 0.27.

The TA/SA ratios in prior art single-spring commercial tape measuredesigns that Applicant is aware of are between 0.98-1.55. The TA/SAratios in prior art multi-spring-in-series commercial tape measuredesigns that Applicant is aware of are between 1.28-1.35 when SA is thecross-sectional area of one of the springs. The TA/SA ratios in priorart multi-spring-in-series commercial tape measure designs thatApplicant is aware of are between 0.64-0.68 when SA is the sum of thecross-sectional areas of each spring.

As will be generally understood, the moment of inertia of metal core 130of tape blade 18 and of spring 24 is related to the thickness cubed (andthe width), and as such the ratio of the moment of inertia of metal core130 of tape blade 18, MIT, and the moment of inertia of spring 24, MIS,provides an indication of the compactness of tape measure 10. In variousembodiments, MIT/MIS is less than 0.68, specifically is less than 0.3,and more specifically is between 0.09 and 0.22. In various embodiments,MIT/MIS is less than 0.8, is less than 0.73, is less than 0.70, is lessthan 0.70, is less than 0.60, is less than 0.50, is less than 0.40, isless than 0.30, is less than 0.20, or is less than 0.10. In specificembodiments, moment of inertia is calculated by assuming that both thespring and the tape blade, when flat, are operating as a rectangularbeam. The equation used is I≈(w t^3)/12, where I is the moment ofinertia, w is the width of the beam, and t is the thickness of the beam.

The MIT/MIS ratios in prior art commercial tape measure designs thatApplicant is aware of are between 0.80-1.85. The MIT/MIS ratios in priorart multi-spring commercial tape measure designs that Applicant is awareof are between 0.69-0.79.

Referring to FIGS. 10 and 12, because spring 24 has a lower length thanconventional tape measure springs, interior reel cavity 124, which issized to hold spring 24, is smaller than in standard tape measuredesigns for a given tape length. The size of interior reel cavity 124can be measured in a variety of ways relevant to evaluating thecompactness of tape measure 10. As shown in FIGS. 10 and 12, the size ofinterior reel cavity 124 is related to the minor diameter, D, of tapereel 20 that is measured across opposing portions of radially outwardfacing surface 120. Similarly, as can be seen in FIG. 12, the size ofinterior reel cavity 124 is related to the cross-sectional area, RA, ofthe region within tape reel 20 that is located within radially outwardfacing surface 120.

In various embodiments, the compactness of tape measure 10 can beevaluated by comparing the length of tape blade 18, TL, to the diameter,D, of surface 120 of tape reel 20. In various embodiments, TL/D isgreater than 165 and in one such embodiment, there is only a single,retraction spiral spring located within tape reel 20. In someembodiments, TL/D is greater than 196. In a specific embodiment, tapemeasure 10 is a 25 foot tape measure in which TL is 25 ft. having a TL/Dratio of greater than 165, and specifically 194.59-213.19. In a specificembodiment, tape measure 10 is a 35 foot tape measure in which TL is 35ft. having a TL/D ratio of 240-250 and specifically of about 243.29. Ina specific embodiment, tape measure 10 is a 40 foot tape measure inwhich TL is 40 ft. having a TL/D ratio of 265-275, and specifically ofabout 271.38. In a specific embodiment, tape measure 10 is a 50 foottape measure in which TL is 50 ft. having a TL/D ratio of 455-465, andspecifically of about 460.38.

Prior art, single spring, 25 foot commercial tape measure designs thatApplicant is aware of have a TL/D ratio between about 157.95-164.62. Oneprior art commercial tape measure design that Applicant is aware of hasa TL/D ratio of 194.80 (25 foot)-236.77 (35 foot), but this prior arttape measure includes two spiral retraction springs, coupled in series,driving retraction of the tape reel. A prior art 40 foot commerciallyavailable tape measure has a TL/D ratio of 217.33.

In some embodiments, TL is less than 29 feet, and specifically is lessthan 27 feet. In various embodiments, TL/D is greater than 195. Invarious embodiments, TL/D is greater than 237. In various embodiments,TL/D is greater than 240. In various embodiments, TL/D is less than 250.

In various embodiments, the compactness of tape measure 10 can beevaluated by comparing the length of tape blade 18, TL, to the area, RA,within surface 120 of tape reel 20. In various embodiments, TL/RA isgreater than 5 and in one such embodiment, there is only a single,retraction spiral spring located within tape reel 20. In someembodiments, TL/RA is greater than 6.2, and in some such embodiments,tape measure 10 includes a single spring. In various embodiments, TL/RAis greater than 6.6. In various embodiments, TL/RA is greater than 6.6,greater than 6.7, or greater than 7. In various embodiments, TL/RA isless than 7 or is less than 7.5. In a specific embodiment, tape measure10 is a 25 foot tape measure in which TL is 25 ft. having a TL/RA ratioof 6.18-7.42. In a specific embodiment, tape measure 10 is a 35 foottape measure in which TL is 35 ft. having a TL/RA ratio of 6.7-7.2, andspecifically of 6.95. In a specific embodiment, tape measure 10 is a 40foot tape measure in which TL is 40 ft. having a TL/RA ratio of 6.2-67,and specifically of 6.58. In a specific embodiment, tape measure 10 is a50 foot tape measure in which TL is 50 ft. having a TL/RA ratio of15-20, and specifically of 17.5.

The TL/RA ratio in prior art, single spring, commercial tape measuredesigns that Applicant is aware of are between about 3.08 and 5.00. Oneprior art commercial tape measure design that Applicant is aware of hasa TL/RA ratio of 6.22 (25 foot)-6.6 (35 foot), but this prior art tapemeasure includes two spiral retraction springs, coupled in series,driving retraction of the tape reel.

Referring to FIG. 11, in contrast to some prior tape designs thatutilize gearing (e.g., long-length, e.g., greater than 50 ft., flattapes, crank-based manual retraction tapes, etc.), in at least someembodiments, the compact designs discussed herein are provided in tapemeasures having highly robust, high standout, concave/convex metal tapeblades. As shown in FIG. 11, tape blade 18 generally and both metal core130 and polymer coating 132 generally define upper surfaces having aconcave profile shape and/or lower surfaces having a convex profileshape. This shape generally provides for increased tape blade rigidityand tape blade standout and, in some embodiments, distinguishes tapemeasure 10 from very long tapes or manual crank type tape measures thathave flat measuring tape blades. In specific embodiments, tape blade 18has a standout (e.g., the length of tape that is self-supporting whenextended from tape housing 12) of at least 4 feet, or at least 6 feet,or of at least 8 feet. In addition, tape blade 18 has one or more ink ormarking layer 134 located between the outer surfaces of metal core 130and polymer coating 132 that provides the various tick marks andmeasurement numerals on tape blade 18.

In specific embodiments, because of the compact nature of spring 24 asdiscussed herein the dimensions of tape measure housing 12 are compactas compared to tape measures having a tape blade of a given length. Inspecific embodiments, tape measure housing 12 has a maximum width (thehorizontal dimension shown in FIG. 10) of 45 mm-63 mm, a maximum height(the vertical dimension shown in FIG. 10) of 69 mm-103 mm, and a maximumlength (the dimension perpendicular to both the width and the height) of78 mm-110 mm. In one embodiment, tape blade 18 has a maximum extendedlength, TL, of 25 feet, and housing 12 has a width of 45 mm to 63 mm, aheight of 69 mm to 89 mm, and a length of 78 mm to 96 mm. In oneembodiment, tape blade 18 has a maximum extended length, TL, of 35 feet,and housing 12 has a width of 45 mm to 63 mm, a height of 79 mm to 101mm, and a length of 89 mm to 110 mm.

The various dimensions of various illustrative embodiments of tapemeasure 10 developed by Applicant are shown in Table 1 below.

TABLE 1 Tape Tape Tape Tape Tape Measure Measure Measure Measure MeasureDimension/Parameter Design 1 Design 2 Design 3 Design 4 Design 5 TapeLength (TL) (ft.) 25.6 25.6 35.6 25.6 40.6 Spring Length (SL) 2321 20892526 2324 2120 (mm) Tape Steel Thickness 0.11 0.11 0.11 0.11 0.11 (TT)(mm) Spring Thickness (ST) 0.18 0.2 0.255 0.22 0.255 (mm) Tape ReelMinor 36.6 36.6 44.6 40.1 45.6 Diameter (D) (mm) Tape Reel Minor Area1052.1 1052.1 1562.3 1262.9 1633.1 (RA) (mm²) Tape Cross-Sectional 2.972.97 2.97 2.97 3.52 Area (TA) (mm²) Spring Cross-Sectional 6.3 7.0 6.3755.5 7.65 Area (SA) (mm²) Tape Moment of 0.003 0.003 0.003 0.003 0.0035Inertia (MIT) (mm⁴) Spring Moment of 0.017 0.0233 0.0345 0.0222 0.0415Inertia (MIS) (mm⁴) Tape Reel Turns to 1.95 2.29 3.18 2.36 3.55 SpringReel Turns

In various embodiments, metal core 130 of tape blade 18 is formed from asteel material, and spring 24 is formed from a steel material. Invarious embodiments, metal core 130 and/or spring 24 are formed from analloyed spring steel, alloyed high strength steel, etc. In oneembodiment, the steel of metal core 130 and/or spring 24 is of ahardness between 50-54 RHC. In another embodiment, the steel inner core130 and/or spring 24 is of a hardness between 45-60 RHC. In specificembodiments, polymer coating 132 is a nylon material, and in specificembodiments, coating 132 may be applied as a laminate, nylon extrusion,film attached with adhesive, or a powder/spray on coating.

Referring to FIGS. 4 and 5, a tape measure reel and a retraction systemare shown according to another illustrative embodiment. In general, theretraction system of FIGS. 4 and 5 is an alternative mechanism that maybe included in tape measure 10. In this embodiment, a gear train 60 iscoupled between tape reel 20 and a spiral spring 62. In variousembodiments (and similar to gear train 30), gear train 60 provides gearreduction between tape reel 20 and spiral spring 62 such that eachrotation of tape reel 20 results in less than one rotation of spiralspring 62. In various embodiments, the gear reduction provided by geartrain 60 is at least 2 to 1, and specifically is 3 to 1 or greater. In aspecific embodiment, the gear reduction provided by gear train 60 isbetween 3 and 4 to 1, and specifically is 3.2 to 1.

In addition, gear train 60 is configured to change the direction of therotational movement of tape reel 20 in order to wind spiral spring 62which does not reside within tape reel 20. As shown in FIG. 4, tape reel20 defines a rotational axis 64 about which tape reel 20 rotates duringextension and retraction, and spiral spring 62 defines rotational axis66 about which spring 62 is wound during tape extension. In variousembodiments, gear train 60 is configured such that tape reel rotationalaxis 64 and spring rotational axis 66 are not parallel to each other,and in a specific embodiment, tape reel rotational axis 64 and springrotational axis 66 are perpendicular to each other. The relativepositioning of tape reel 20 and spring 62 provided by gear train 60allows for the overall height of the tape measure 10 incorporating thisretraction mechanism to be lower than tape measures in which therotational axes of the tape reel and spring are parallel or in which thespiral spring is located within tape reel 20.

In specific embodiments, gear train 60 includes first gear 70 rigidlycoupled to tape reel 20 and includes gear teeth surrounding rotationalaxis 64. First gear 70 engages and drives a first bevel gear 72, whichin turn engages and drives a second bevel gear 74. As shown in FIG. 5,second bevel gear 74 is located perpendicular to first bevel gear 70 andincludes a central post 76. An inner end of spiral spring 62 is coupledto post 76, and an outer end of spiral spring 62 is coupled to a fixedposition relative to the housing of the associated tape measure. In thisarrangement, central post 76 is rigidly fixed to second bevel gear 72such that post 76 defines spring rotational axis 66. As second bevelgear 74 is driven by tape reel 20 through gears 70 and 72, second bevelgear 74 and post 76 rotates which in turn winds spiral spring 62 duringtape extension. Upon release of the tape, spring 62 drives reel 20through gears 74, 72 and 70 driving retraction of the tape blade ontotape reel 20.

Referring to FIGS. 6-9, various embodiments of tape measure 10 includinga compression spring based retraction system are shown and described. Inone illustrative embodiment shown in FIGS. 6 and 7, tape measure 10includes a retraction system 80, and retraction system 80 includes acompression spring (e.g., an axial compression spring, a helicalcompression spring, a wave spring, leaf spring, conical shaped springs,hourglass-shaped springs, barrel-shaped springs, etc.), shown as helicalcompression spring 82, and a system for transmitting rotational movementof tape reel 20 (e.g., during tape extension) to non-rotational (e.g.,axial) compression of spring 82. In such embodiments, Applicant believesthat for a tape blade of a given size or for a spring of a given energylevel, use of retraction system 80 including a compression spring allowsfor a more compact tape measure.

As shown in FIGS. 6 and 7, retraction system 80 includes a plate 84 thatengages one end of spring 82. The inner surface of tape reel 20 includesgear teeth 86 that engage cooperating gear teeth 88 formed on the outerperimeter of plate 84 such that rotational movement of tape reel 20during tape extension is transferred to plate 84. Retraction system 80includes a transmission system, shown as threaded post 90, that covertsrotational motion of tape reel 20 to axial compression of spring 82.

Plate 84 includes a threaded central opening 92 which engages threads 94located along the outer surface of threaded post 90. As plate 84 isrotated via engagement between gear teeth 86 and 88, plate 84 movesaxially, along the length of post 90 such that plate 84 compressesspring 82 during tape extension. When the tape blade (e.g., tape blade18) is released, spring 82 expands driving the components in theopposite direction causing tape reel 20 to wind up the tape blade.

As will be understood, the thread pitch of threads 94 determines thedegree of conversion between rotational movement and axial movement ofplate 84. Thus, the thread pitch of threads 94 determines the degree oramount of compression experienced for each rotation of tape reel 20.Thus, in various embodiments, the pitch of threads 94 is selected toprovide a desired level of spring compression, and consequently adesired level of retraction force, which in turn can limit tape whip andthe potential tape damage associated with tape whip.

Referring to FIGS. 8 and 9, another embodiment of tape measure 10including a compression spring based retraction system, such asretraction system 100, is shown and described. In general, retractionsystem 100 is substantially the same as retraction system 80 discussedabove, except for the differences discussed herein. Similar to system80, retraction system 100 is configured to transmit rotational movementof tape reel 20 (e.g., during tape extension) to non-rotational (e.g.,axial) compression of spring 82.

System 100 includes a compression plate 102 and threads 104 locatedalong the internal surface of tape reel 20. Compression plate 102includes an outer perimeter wall or sidewall 106 that extends betweenopposing major surfaces or faces 108 and 110. Compression plate 102includes external threads 112 located along outer sidewall 106. Ingeneral, external threads 112 are sized to cooperate with internalthreads 104 such that as reel 20 rotates (e.g., during tape extension)interaction between threads 104 and threads 112 drives plate 102 axiallyalong shaft 114 causing spring 82 to be compressed. As will beunderstood, in general, plate 102 is rotatably coupled to shaft 114 suchthat plate 102 is permitted to rotate around shaft 114 and is also ispermitted to translate along shaft 114. In specific embodiments, shaft114 has a circular cross-section shape and is received through acircular central mounting hole in plate 102. As will be understood, oncethe tape blade is released, spring 82 expands against plate 102 which inturn drives rotation of tape reel 20 in the opposite direction causingthe tape blade (e.g., tape blade 18) to retract and wind onto tape reel20. In specific embodiments, shaft 114 is fixed, and as tape reel 20spins around shaft 114 within the tape housing, plate 102 moves linearlyalong shaft 114.

As shown in FIGS. 8 and 9, threads 104 are recessed threads forming ahelical pattern along the inner surface of tape reel 20. Threads 112 areexternal threads extending outward from sidewall 106 and formed in ahelical pattern that matches the helical pattern of threads 104. In thismanner, threads 112 ride within threads 104 as plate 102 translatesalong shaft 114 during tape extension and retraction.

It should be understood that the figures illustrate the illustrativeembodiments in detail, and it should be understood that the presentapplication is not limited to the details or methodology set forth inthe description or illustrated in the figures. It should also beunderstood that the terminology is for the purpose of description onlyand should not be regarded as limiting.

Further modifications and alternative embodiments of various aspects ofthe invention will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only. The construction and arrangements, shown in thevarious exemplary embodiments, are illustrative only. Although only afew embodiments have been described in detail in this disclosure, manymodifications are possible (e.g., variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter described herein. Someelements shown as integrally formed may be constructed of multiple partsor elements, the position of elements may be reversed or otherwisevaried, and the nature or number of discrete elements or positions maybe altered or varied. The order or sequence of any process, logicalalgorithm, or method steps may be varied or re-sequenced according toalternative embodiments. Other substitutions, modifications, changes andomissions may also be made in the design, operating conditions andarrangement of the various illustrative embodiments without departingfrom the scope of the present invention.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is in no way intendedthat any particular order be inferred. In addition, as used herein, thearticle “a” is intended to include one or more component or element, andis not intended to be construed as meaning only one. As used herein,rigidly coupled refers to two components being coupled in a manner suchthat the components move together in fixed positional relationship whenacted upon by a force.

Various embodiments of the invention relate to any combination of any ofthe features, and any such combination of features may be claimed inthis or future applications. Any of the features, elements, orcomponents of any of the illustrative embodiments discussed above may beutilized alone or in combination with any of the features, elements, orcomponents of any of the other embodiments discussed above.

What is claimed is:
 1. A tape measure comprising: a housing; a tape reelrotatably mounted within the housing, the tape reel comprising aradially outward facing surface and a radially inward facing surfacedefining an interior reel cavity; an elongate tape blade wound aroundthe radially outward facing surface of the tape reel, wherein theelongate tape blade comprises a metal core and a coating layer, and themetal core has an average cross-sectional area, TA; and a spring coupledto the tape reel such that when the elongate tape blade is unwound fromthe tape reel to extend from the housing the spring stores energy andthe spring releases energy driving rewinding of the elongate tape bladeon to the tape reel, wherein the spring has an average cross-sectionalarea, SA, wherein TA/SA is less than 0.9.
 2. The tape measure of claim1, wherein TA/SA is less than 0.75.
 3. The tape measure of claim 1,further comprising a total spring length, SL, wherein the elongate tapeblade has a maximum extended length, TL, wherein TL/SL is greater than2.52.
 4. The tape measure of claim 3, wherein TL/SL is between 3 and 15.5. The tape measure of claim 4, wherein TL is between 6 feet and 50feet, and SL is between 5 feet and 23 feet.
 6. The tape measure of claim3, wherein TL/SL is greater than 3.7.
 7. The tape measure of claim 3,wherein the tape measure has only one spring.
 8. The tape measure ofclaim 3, wherein the tape measure comprises a shaft coupled to thehousing, wherein the tape reel rotates around the housing.
 9. The tapemeasure of claim 8, wherein the shaft is fixed to the housing.
 10. Thetape measure of claim 1, wherein the shaft is permitted to rotaterelative to the housing.
 11. The tape measure of claim 1, wherein thetape reel comprises a diameter, D, measured across the radially outwardfacing surface of the tape reel, wherein the elongate tape blade has atotal maximum extended length of TL, wherein TL/D is greater than 165.12. The tape measure of claim 11, wherein TL/D is greater than
 196. 13.The tape measure of claim 12, wherein the spring is a spiral spring, andthere is only one spiral spring located within the interior reel cavity.14. The tape measure of claim 1, further comprising a turn differentialmechanism coupling the spring to the tape reel such that, duringextension of the elongate tape blade from the housing, each fullrotation of the tape reel is translated into less than a full rotationof the spring.
 15. The tape measure of claim 14, wherein the spring is aspiral spring and is at least partially located within the interior reelcavity and is at least partially surrounded by the elongate tape bladein the radial direction, wherein the turn differential mechanism is areduction gear train, wherein at least one gear of the reduction geartrain is at least partially surrounded by the elongate tape blade in theradial direction.
 16. A tape measure comprising: a housing; a tape reelrotatably mounted within the housing, the tape reel comprising aradially outward facing surface and a radially inward facing surfacedefining an interior reel cavity; an elongate tape blade wound aroundthe radially outward facing surface of the tape reel, wherein theelongate tape blade has a maximum extended length, TL; a spring coupledto the tape reel such that, when the elongate tape blade is unwound fromthe tape reel to extend from the housing, the spring stores energy andthe spring releases energy driving rewinding of the elongate tape bladeon to the tape reel; and a total spiral spring length, SL; wherein TL/SLis greater than 2.52.
 17. The tape measure of claim 16, wherein TL/SL isbetween 3 and
 15. 18. The tape measure of claim 17, wherein TL isbetween 6 feet and 50 feet, and SL is between 5 feet and 23 feet. 19.The tape measure of claim 16, wherein the elongate tape blade comprisesa metal core and a coating layer, and the metal core has an averagecross-sectional area, TA, wherein the spring has an averagecross-sectional area, SA, wherein TA/SA is less than 0.9.
 20. The tapemeasure of claim 19, wherein TA/SA is less than 0.75.
 21. The tapemeasure of claim 16, wherein the tape reel comprises a diameter, D,measured across the radially outward facing surface of the tape reel,wherein the elongate tape blade has a total maximum extended length, TL,wherein TL/D is greater than
 165. 22. The tape measure of claim 21,wherein TL/D is greater than
 196. 23. The tape measure of claim 21,wherein the spring is a spiral spring and there is only one spiralspring located within the interior reel cavity.
 24. The tape measure ofclaim 16, further comprising a turn differential mechanism rotatablycoupling the spring to the tape reel such that, during extension of theelongate tape blade from the housing, each full rotation of the tapereel is translated into less than a full rotation of the spring.
 25. Thetape measure of claim 24, wherein the spring is a spiral spring, whereinthe spiral spring is at least partially located within the interior reelcavity and at least partially surrounded by the elongate tape blade inthe radial direction, wherein the turn differential mechanism is areduction gear train, wherein at least one gear of the reduction geartrain is at least partially surrounded by the elongate tape blade in theradial direction.